1. Field of the Invention
This invention is in the field of apparatus and methods for use in accelerating the activity of dental bleaching compositions. More particularly, the invention is in the field of apparatus and methods for accelerating the activity of e.g., dental bleaching, desensitizing and remineralizing compositions by means of a heated dental impression material.
2. Review of the Relevant Technology
In the last decade there has been a proliferation of compositions and methods for bleaching teeth. Compositions for both in-office or at-home use typically include a peroxide bleaching agent, such as carbamide peroxide, hydrogen peroxide or sodium perborate. Carbamide peroxide is a complex of urea and hydrogen peroxide. Sodium perborate is a complex of sodium borate and hydrogen peroxide. On the other hand, hydrogen peroxide by itself only exists in aqueous form and is generally unstable except at relatively low pH.
When forming an appropriate bleaching composition there is inherently a trade-off between stability and reactivity. It is desirable for a bleaching composition to remain stable between the time when it is manufactured and when it is used to bleach a person""s teeth. However, once placed on a person""s teeth it is desirable for the composition to quickly break down and release active oxygen radicals capable of bleaching teeth. In general, compositions that are sufficiently stable so as to have good shelf life tend to bleach teeth slowly over time, typically over a period of weeks with daily regimens of from one to eight hours. On the other hand, bleaching compositions that are capable of bleaching teeth in shorter periods of time generally do not have a long shelf life and are typically prepared just prior to application to a person""s teeth.
There are at least two known ways of triggering accelerated decomposition of active oxygen radicals from peroxide-containing bleaching compositions. One way is through the use of chemicals or catalysts that are known to destabilize peroxides. Such agents are typically mixed in with the peroxide bleaching agent just prior to application to the person""s teeth.
Another way to accelerate the bleaching activity of peroxide-based bleaching compositions is through the application of heat. Examples of apparatus used to generate heat include conventional dental curing lamps used to cure composites and lasers. A draw-back that is common to both curing lamps and lasers is that it is typically not possible to simultaneously heat all of a patient""s teeth, thus increasing the time it takes to complete the bleaching process as well as leading to the possibility of unequal application of heat to the various teeth. Another drawback to the use of a curing law, particularly one that is able to focus light or heat energy to an area that is greater than the size of the labial surface of a tooth to be bleached, is that the curing lamp tends to be indiscriminate as to whether it heats the tooth or surrounding gingival tissue, thus potentially causing discomfort to the patient. Accordingly, it is typically necessary to protect the patient""s gingival tissue through the use of a protective rubber dam coating material.
In the case of at-home bleaching regimens, a customized patient bleaching tray or mouth guard is typically formed using a multi-step procedure. This procedure typically includes the steps of (1) making conventional alginate impressions of the patient""s maxillary and/or mandibular teeth, (2) preparing stone cast models of the patient""s upper and lower teeth from the alginate impressions using plaster of paris, followed by trimming away of the excess plaster, (3) blocking out on the trimmed cast stone models, using a conventional light-cured or light-activated, acrylic-based resin laboratory block-out gel, those tooth areas to be whitened so as to form reservoirs in the resulting tray, (4) vacuum forming a 5-inch by 5-inch sheet of 0.040-inch to 0.080-inch thickness clear plastic resin mouth guard material over each stone cast model, (5) removing the tray from the model, and (6) suitably trimming the tray so that it doesn""t overlap the gingival margin. In some cases the tray is xe2x80x9cscallopedxe2x80x9d by trimming up and around the dental papilla. The dental tray is then ready for delivery to the patient as part of the home-use whitening kit. Home-use bleaching regimens employing the custom dental tray and whitening composition (e.g., a carbamide peroxide gel) typically involves a series of 1 to 8 hour bleaching treatments repeated daily over a period of about 2 to 6 weeks depending upon the degree or severity of dentition staining.
In view of the foregoing, there has been a long felt need in the art to provide apparatus and methods for use in accelerating the bleaching activity of conventional bleaching compositions in a manner that is both more comfortable from the point of view of the patient and more economical in terms of cost and time. It would be particularly useful of such apparatus were disposable, that is, of sufficiently low cost and simplicity of design so that it could be used for a single patient and then disposed of.
It would be a further advancement in the art if the foregoing apparatus and methods could be used to accelerate the activity of other dental compositions, e.g., desensitizing and/or remineralizing compounds that include potassium nitrate and/or fluoride salts.
Such apparatus and methods for increasing the activity of bleaching, desensitizing and remineralizing or other dental compositions are disclosed and claimed herein.
The present invention relates to apparatus and methods used to accelerate the activity of dental compositions by means of the application of heat. In particular, the invention relates to apparatus and methods for treating teeth that involve conventional or specially adapted dental impression trays in conjunction with a heated impression material. The use of impression material provides the dentist with the ability to manufacture what is, in essence, a customized tray that can be immediately used to treat a patient""s teeth using a variety of dental compositions, (e.g., dental bleaching, desensitizing, or remineralizing compositions). The formed impression material can be heated by, e.g., microwave energy, resistive heating devices, or a heated fluid in order to accelerate the rate at which the dental composition is able to carry out its intended treatment of a patient""s teeth.
The apparatus according to the present invention may advantageously be sold or provided to a dentist in the form of one or more kits that include at least a portion of the means necessary to form and then heat a dentition impression of the patient""s teeth, followed by treatment of a patient""s teeth using an appropriate dental composition. Such kits will preferably include, at a minimum, a dental impression tray capable of receiving sufficient impression material so as to make an impression of at least a portion of the patient""s teeth, means for heating the impression during the treatment process, and one or more dental compositions, such as compositions that include at least one of a dental bleaching agent (e.g., a peroxide bleaching agent), a desensitizing agent (e.g., a potassium salt such as potassium nitrate), or a remineralizing agent (e.g., a fluoride salt such as sodium fluoride). The kits may optionally include an impression material, such as a standard alginate impression material known in the art. Nevertheless, because most dentists already have standard impression materials on site for other purposes, it is typically not necessary for the kits to include such impression materials.
A preferred embodiment of utilizing the apparatus disclosed herein to carry out accelerated treatment of a patient""s teeth includes the following steps: (1) filling at least a portion of a dental impression tray with an unset dental impression material; (2) placing the filled dental impression tray into the patient""s mouth in order to take an impression of at least a portion of the patient""s teeth; (3) maintaining the impression tray in place for a sufficient length of time for the dental impression material to at least partially cure to thereby form a patient dentition impression; (4) removing the dental impression tray and included formed patient dentition impression from the patient""s mouth; (5) placing an appropriate quantity of a dental composition within the formed patient dentition impression; (6) introducing the dental impression tray and included formed patient dentition impression with the dental composition into the patient""s mouth so as to at least approximately register the patient""s teeth and the corresponding formed patient dentition impression; (7) heating and/or maintaining the temperature of the formed patient dentition impression at a temperature of at least about 105xc2x0 F.; and (8) removing the dental impression try and included dentition impression from the patient""s mouth and thoroughly rinsing the patient""s mouth prior to release of the patient.
In a preferred embodiment, the formed patient dentition impression will be heated to and maintained at the desired temperature by means of an electrical resistance heating element located within, or otherwise associated with, the dental impression tray. The dentition impression may alternatively be heated by means of microwave energy or by the use of a heated fluid. The temperature of the dentition impression is preferably maintained in a range of about 110xc2x0 F. to about 150xc2x0 F., more preferably in a range of about 120xc2x0 F. to about 140xc2x0 F.
In the case where an electrical resistance heating element is used, the dental impression tray will be electronically connected to a power supply, such as a DC power supply that supplies a desired amount of power. In a preferred embodiment, the patient may be given a control device that interacts with the power supply so as to heat and maintain the dentition impression at an elevated, yet comfortable, temperature so as to optimize patient comfort and dental composition activity. In order to further maximize patient comfort, it may be advantageous to trim away a portion of the patient dentition impression that would otherwise contact or overlap the patient""s gingival tissue. In this way the heat can be concentrated or focused on the teeth and kept away from the much more sensitive gingival tissue surrounding the teeth.
The treatment times according to the present invention typically range of about 1 minute to about 60 minutes, more preferably in a range of about 5 minutes to about 30 minutes, depending on the dental composition being used, as well as the time necessary for carrying out a desired treatment. Where it has heretofore been known that heat is able to destabilize peroxide-based dental bleaching agents so as to accelerate the liberation of oxygen radicals used in bleaching teeth, it has heretofore not been known that heat can also accelerate the beneficial effects of other dental agents, such as desensitizing agents based on potassium trate or remineralizing agents based on fluoride salts. This is a surprising result since neither potassium nitrate nor fluoride salts decompose when heated to the temperatures described herein.
Accordingly, it is an object of the invention to provide apparatus and methods for use in accelerating the bleaching activity of conventional bleaching compositions in a manner that is both more comfortable from the point of view of the patient and economical in terms of cost and time.
It is a further object to provide apparatus that is disposable and that is of sufficiently low cost and simplicity of design so that it can be used for a single patient and then disposed of.
It is a further object of the invention to provide apparatus and methods that can be used to accelerate the activity of other dental compositions, such as desensitizing and/or remineralizing compounds that include potassium nitrate and/or fluoride salt.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.